High-velocity swaging

ABSTRACT

A method of forming metal members by accelerating the metal member to a predetermined high forming velocity, and then contacting the metal member with the forming die which is restrained relative to the metal member to effect forming of the metal member. In particular tubular metal members can be swaged within a forming die having a generally conical central aperture therethrough, with the aperture tapering from a diameter at the die entry which is greater than the outside diameter of the tubular metal member, to a predetermined lesser diameter at the other end of the forming die, whereby the metal member is formed.

United States Patent 1 nu 3,756,062 Merola 1 Sept. 4, 1973 [54] HIGH-VELOCITY SWAGING 3,691,625 9/1972 Swenck 29/557 738,932 9 1903 CD 11... 72 284 [75] Inventor Anthmy Mew, Plmburgh, 3 668 916 6/1972 Led l a i i j 72/284 [73] Assignee: Amerola Products Corporation,

5 Pittsburgh, Pa. Primary Examiner-Richard J. Herbst [22] Filed: June 21 1971 AttorneyEdward L. Welsh [21] Appl. No.: 154,812 [57] ABSTRACT A method of forming metal members by accelerating [52] US. Cl. 72/352, 72/367 the metal member to a predetermined high furming [51] 821d 51/10 locity, and then contacting the metal member with the [58] FIG of Search 72/343, 354, 367, forming die which is restrained relative to the meta] 72/37O' 352; ZQIDIG' 41 member to effect forming of the metal member. ln particular tubular metal members can be swaged within a [56] References cued forming die having a generally conical central aperture UNITED STATES PATENTS therethrough, with the aperture tapering from a diame- 3,l65,199 1/ 1965 Tlaker 72/370 ter at the die entry which is greater than the outside di- 8l,478 8/1868 Cranston.. 72/352 ameter of the tubular metal member, to a predeter- 2,958,115 11/1960 y mined lesser diameter at the other end of the forming Hilton et al..... die whereby the metal member is fon-ned 3,269,167 8/1966 Hertel et al..... 72/56 3,382,738 5/1968 Copeland 76/892 11 Claims, 2 Drawing Figures Patented Sept. 4, 1973 mm W INVENTOR ANTHONY MEROLA HIGH-VELOCITY SWAGING BACKGROUND OF THE INVENTION The traditional method of swag-forming metal members has been to exert a swaging force on the member by striking or contacting the member with a die or plurality of dies of considerable mass moving at low velocity. The resultant swaging force effects the metal forming as is well known in the art.

Recent technological advances in the metal forming art are outlined in High-Velocity Forming of Metals" edited by E. J. Bruno and published in 1968 by the American Society of Tooling and Manufacturing Engineers. The term high velocity forming has been applied to three distinct techniques which have in common increasing the forming force by concentrating on increasing the velocity factor in the standard kinectic energy equation F r mV. These high velocity forming techniques include electromagnetic forming, explosive forming, and pneumatic-mechanical forming. The term high velocity has been taken to mean a forming velocity of greater than about fifty feet per second. Such high velocity forming techniques have been applied in expanding metal members, forming ribs in tubular members, and similar operations. In such techniques, the workpiece is disposed within the forming die in a chamber, and then an electromagnetic force or shock wave is generated within the chamber forcing the workpiece into a closely disposed forming die to form it to a predetermined configuration.

The conventional swaging operation can be a time consuming operation which impedes high volume production. The clapping hammers of a conventional swaging apparatus repetitively strike the outer surface of a tubular member to effect the swaging. The outer surface of a swaged tubular member must then be finished, and any further work on the piece, such as anodizing of aluminum tubes must be done after the swaging. This can mean a great inconvenience because if the swag-former does not have all the finishing equipment on site, it means transhipment of the swaged workpiece back to a metal processor for these finishing operations.

The interior surface of a generally tubular member which has been subjected to conventional swag forming, exhibits innumerable cracks or fractures which run parallel to the longitudinal axis of the swaged member. These cracks or fractures are evidence of a weakened condition of the metal member.

It has been surprisingly discovered that when a generally tubular metal member is swaged using the method of the present invention, such cracks or fractures parallel to the longitudinal axis of the swaged member are eliminated. The interior wall surface of the member swaged following the present invention does exhibit circumferential lines, but the interior surface remains relatively smooth and significantly smoother than a conventionally swaged tube. This relatively smooth interior wall surface can be important when the interior wall of the swaged member is contacted such as by fluids passing through the member during use of the member.

Swaged, generally tubular metal members find a wide variety of commercial applications ranging from metal ball bats and pool cue segments to chair and table legs for kitchen and dinette sets.

SUMMARY OF THE INVENTION In the method of the present invention a tubular metal member can be very quickly and conveniently swaged by accelerating the tubular metal member to a predetermined forming velocity relative to a forming die, and then passing the member into the forming die which is restrained from movement. The forming die has a generally conical die cavity therein, with the diameter at the die entry greater than the initial outside diameter of the tubular metal member, with the die cavity diameter tapering to a predetermined lesser diameter, whereby the tubular metal member is swaged to conform to the generally conical die cavity.

A novel apparatus for practicing the method is also described.

Some rather surprising results are achieved in practicing the high velocity swaging of the present invention. It has been observed that for an aluminum tube that is to be swaged to form a portion of an aluminum pool cue, that the aluminum tube can be anodized prior to the high velocity swaging operation. The anodized surface is not adversely affected or altered by the forming die when the aluminum tube is accelerated to the high forming velocity and formed in the die according to the present invention. In fact, lettering on the surface of such aluminum tube is remarkably undisturbed on the tube surface, and is only affected to the extent that the surface at that point has been reformed. In a specific example of the method of the present invention, tubular aluminum can be swaged to provide a tapered member for use as a pool cue segment, a chair or table leg, or other such use.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of a set-up for practicing the present invention.

FIG. 2 is a sectional view of the forming die with the swaged metal member still disposed therein.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention can be better understood by referring to the exemplary embodiment represented in the drawmgs.

' In carrying out the method, the tubular metal member 10 can be accelerated to the forming velocity by any number of a variety of propulsion means. Thus, in a specific example, aluminum tubing 10 which is 606l-T6 grade aluminum of 1.25 inches o.d., and a wall thickness of approximately 0.083 inches, in 10 inch long pieces is swaged over the 10 inch length. The tube is swaged so that the outside diameter of the swaged tube varies from the original 1.25 inches at one end, to about 0.94 inches at the other end. The tubing is disposed in a vertical position several feet above the forming die 1 l, and with about pounds of additional weight affixed to the tube by attaching a metal rod 12 to the vertically extending top end of the tube. The forming die 11 is restrained from movement relative to the accelerated tube, and comprises a body portion with a generally .conical die cavity 13 therein. The diameter of the die cavity entry end is slightly greater than the 1.25 inch o.d. of the tube used in this specific instance. The die cavity diameter tapers down to the 0.94 inch value. The forming die can have a quick opening capacity to allow for rapid removal of the swaged metal member. Thus, for example, forming die 11 shown in FIG. 1 comprises a left side and right side which open along mating line 18. A plurality of such forming dies could also be used with one being indexed into position to receive the accelerated metal member, while other such forming dies are indexed to separate stations where the metal member is removed from the respective forming die.

A vertically extending tubular guide means 14 is provided above the forming die to insure that tube is directed into the conical die cavity. The tubular guide means 14 has an inside diameter slightly greater than the outside diameter of the tube 10. The inside surface of guide means 14 is well lubricated or formed of a material which minimizes frictional resistance.

An accelerating means 15 is included for accelerating the tubular metal member 10 to the desired forming velocity. The accelerating means 15 shown comprises a pair of drive wheels 16 connected to a power source, not shown, for rotating the drive wheels 16 at high speed. The drive wheels 16 are driven to synchronously rotate in opposite directions with a predetermined space between the outer perimeter of each wheel. The spacing is such that the tubular member 10 is fed into the space, frictionally engaged by the wheels and is accelerated by the drive wheels to the desired forming velocity. The dr've wheels are driven at, for example, about 100 mil s per hour, which is about 147 feet per second, and this is substantially the velocity imparted to the tubular member 10. Of course, the frictional engagement will reduce the velocity imparted to the tube but not appreciably. Tubular guide means 14 are included between the accelerating means 15 and the forming die to direct the accelerated tubular member 10 to the generally conical cavity 13 in the forming die.

The specific forming velocity to which the member is to be accelerated to effect the swaging is, of course, dependent upon the following factors, the specific metal and temper used, the diameter of the tubing, the length of tubing to be swaged, and the wall thickness of tubing used.

in FIG. 2 there is an enlarged sectional view of the forming die 11 with the swaged metal member 17 still disposed therein. it should be observed that the wall thickness of the swaged metal member 17 increases as the diameter of the member decreases.

- The method and apparatus of the present invention can be used in preparing superior swaged] metallic members. In practicing the invention, substantially the entire length of the tubularmember can be swaged, or only a portion thereof. The invention has, by way of example, been described with respect to tubular aluminum, but other swagable metals can be used.

I claim:

1. Method of high-velocity swaging tubular metal members in a forming die having an elongated, generally conical die cavity therein, wherein the die cavity entrance diameter is greater than the metal member diameter to accept the metal member, the die cavity diameter tapers to a progressively smaller diameter, which method comprises:

a. accelerating linearly the tubular metal member to a predetermined high forming velocity relative to the forming die, which velocity is sufficient to effect swaging of the tubular metal member upon contact with the die, and

' b. passing the accelerated tubular metal member into the forming die which is restrained relative to the accelerated metal member.

2. The method specified in claim 1, wherein the tubular metal member is accelerated by drive means which frictionally engage and drive the tubular metal memher.

3. The method specified in claim 1, wherein the ac celerated tubular metal member is directed through tubular guide means which insure that the tubular metal member is directed into the conical die cavity.

4. The method specified in claim 1, wherein the forming die is indexed to a tube rem'oval station while another forming die is indexed into position to receive an accelerated tubular member.

5. The method specified in claim I, wherein the tubular metal member is formed of aluminum.

6. Method of high-velocity forming a swaged aluminum conical tube, devoid of visual cracks or fractures in the direction of the axis of the tube, in a forming die comprising:

a. accelerating an aluminum tube to a predetermined high swaging velocity relative to the forming die,

b. passing the accelerated aluminum tube, in the direction of the tube axis, into an elongated, generally conical die cavity of the forming die, which die is restrained relative to the accelerated aluminum tube, the diameter of the die cavity at the entrance thereof being greater than the outside diameter of the aluminum tube with said cavity tapering to a lesser size and the diameter becoming progressively smaller to a diameter less than the outside diameter of the aluminum tube, whereby a portion of the accelerated aluminum tube contacts the walls of the die cavity and the tube is swaged to conform to the elongated, generally conical die cavity.

7. Apparatus for high-velocity swaging a metal tube comprising:

a. means for accelerating a metal tube to a predetermined high swaging velocity; and

b. a forming die spaced from the accelerating means and having a generally conical die cavity therein, with the longitudinal axis of the die cavity aligned with the longitudinal axis of the accelerated metal tube, the die cavity having an entrance diameter larger than the metal tube diameter, with the die cavity diameter decreasing in size from the entrance end, whereby the accelerated tube is swaged to conform to the generally conical die cavity.

8. The apparatus specified in claim 7, wherein a guide means is positioned intermediate the accelerating means and the die cavity, aligned with the longitudinal axis of the die cavity and the accelerated metal tube to guide the metal tube into the die cavity.

9. An apparatus as defined in claim 7, wherein said accelerating means comprises a pair of cooperating rotatable discs which frictionally engage the metal tube and accelerate said tube, whereby a sufficient linear swaging velocity is achieved.

10. An apparatus as defined in claim 7, wherein said forming die is comprised of separable mating parts to enable removal of a swaged metal tube therefrom by separating said parts.

11. The method specified in claim 1, wherein said metal member is accelerated to a velocity of about 147 feet per second.

l l l 

1. Method of high-velocity swaging tubular metal members in a forming die having an elongated, generally conical die cavity therein, wherein the die cavity entrance diameter is greater than the metal member diameter to accept the metal member, the die cavity diameter tapers to a progressively smaller diameter, which method comprises: a. accelerating linearly the tubular metal member to a predetermined high forming velocity relative to the forming die, which velocity is sufficient to effect swaging of the tubular metal member upon contact with the die, and b. passing the accelerated tubular metal member into the forming die which is restrained relative to the accelerated metal member.
 2. The method specified in claim 1, wherein the tubular metal member is accelerated by drive means which frictionally engage and drive the tubular metal member.
 3. The method specified in claim 1, wherein the accelerated tubular metal member is directed through tubular guide means which insure that the tubular metal member is directed into the conical die cavity.
 4. The method specified in claim 1, wherein the forming die is indexed to a tube removal station while another forming die is indexed into position to receive an accelerated tubular member.
 5. The method specified in claim 1, wherein the tubular metal member is formed of aluminum.
 6. Method of high-velocity forming a Swaged aluminum conical tube, devoid of visual cracks or fractures in the direction of the axis of the tube, in a forming die comprising: a. accelerating an aluminum tube to a predetermined high swaging velocity relative to the forming die, b. passing the accelerated aluminum tube, in the direction of the tube axis, into an elongated, generally conical die cavity of the forming die, which die is restrained relative to the accelerated aluminum tube, the diameter of the die cavity at the entrance thereof being greater than the outside diameter of the aluminum tube with said cavity tapering to a lesser size and the diameter becoming progressively smaller to a diameter less than the outside diameter of the aluminum tube, whereby a portion of the accelerated aluminum tube contacts the walls of the die cavity and the tube is swaged to conform to the elongated, generally conical die cavity.
 7. Apparatus for high-velocity swaging a metal tube comprising: a. means for accelerating a metal tube to a predetermined high swaging velocity; and b. a forming die spaced from the accelerating means and having a generally conical die cavity therein, with the longitudinal axis of the die cavity aligned with the longitudinal axis of the accelerated metal tube, the die cavity having an entrance diameter larger than the metal tube diameter, with the die cavity diameter decreasing in size from the entrance end, whereby the accelerated tube is swaged to conform to the generally conical die cavity.
 8. The apparatus specified in claim 7, wherein a guide means is positioned intermediate the accelerating means and the die cavity, aligned with the longitudinal axis of the die cavity and the accelerated metal tube to guide the metal tube into the die cavity.
 9. An apparatus as defined in claim 7, wherein said accelerating means comprises a pair of cooperating rotatable discs which frictionally engage the metal tube and accelerate said tube, whereby a sufficient linear swaging velocity is achieved.
 10. An apparatus as defined in claim 7, wherein said forming die is comprised of separable mating parts to enable removal of a swaged metal tube therefrom by separating said parts.
 11. The method specified in claim 1, wherein said metal member is accelerated to a velocity of about 147 feet per second. 